Simpson Desert

Wind built the long sand dunes here.

The dunes run side by side.

The U.S. Geological Survey explains that linear dunes are long, straight or slightly wavy ridges of sand, often in sets of parallel ridges. Kathryn Fitzsimmons of the Australian National University explains that they form in line with the winds that move sand.

In the Simpson Desert, parallel dunes can stretch for up to 200 kilometers, South Australia's parks service says. Between them lie low valleys called swales, which collect more water than the dune tops.

USGS: linear dunes are straight or slightly sinuous sand ridges, typically much longer than wide, sometimes over 160 km long, usually in parallel sets separated by interdune corridors; many form in bidirectional wind regimes. Fitzsimmons (ANU, SERC): linear dunes form parallel to the resultant vector of sand-shifting winds and cover about one-third of Australia.

For the Simpson Desert she cites Hollands et al. (2006): dunes oblique to today's winds formed between about 74,000 and 14,000 years ago, dunes matching today's winds began between about 14,000 and 10,000 years ago, and the wind whorl has shifted south by about 1-1.5 degrees since the Last Glacial Maximum.

Spinifex grass grows on the sand. After rain, wildflowers can cover the dunes.

Many of the desert's mammals come out only at night, when it is cooler.

South Australia's parks service says sandhill cane-grass grows on the dune crests and spinifex on the steadier sand, while bigger shrubs such as mulga and gidgee grow in the swales between dunes. Many plants grow, flower and set seed within a couple of months of rain, and the dunes can be covered in wildflowers.

More than 150 kinds of birds live in the desert. To escape the heat, many mammals, such as small dunnarts and the ampurta, come out only at night. Perenties, sand goannas and central bearded dragons live here too.

NPWS SA: sandhill cane-grass on dune crests; lobed spinifex (Triodia) on stable sands, its tussocks often forming donut shapes as the center dies; eremophila, grevillea, mulga and gidgee in the swales; samphire around playa lakes; short plant life cycles after rain (poached-egg daisy, fleshy groundsel).

Over 150 bird species (another NPWS page says 195 recorded), including the eyrean grasswren on dune slopes and the rare Australian bustard; nocturnal dunnarts and ampurta; dingoes; perentie, sand goanna, bearded dragons, woma python; feral rabbits, camels and foxes.

Aboriginal people have lived in and around this desert for a very long time.

They found water at native wells called mikiri.

South Australia's parks service says the Wangkangurru people lived in the desert, gathering in family groups around native wells called mikiri, which gave the only permanent water. In good seasons they spread out across the desert after rain.

They traded widely with groups to the north and south, swapping stone axes, grinding stones and ochre. All Aboriginal sites in the park are protected.

NPWS SA: before the 19th century the Wangkangurru lived in the desert, and the Lower Southern Arrernte on and partly in its western edge; family groups centered on native wells (mikiri), the only permanent water, dispersing in good seasons to use groundwater and post-rain growth. They were hunter-gatherers who traded extensively: ground-edge axes from Queensland quarries, sandstone grinding stones and ochre from the North Flinders Ranges. Stone implements occur in the park but are not common; all Aboriginal sites are protected.

The desert parks close in the hottest months. It can get very, very hot.

Wear a wide hat and loose clothes, and rest in the shade.

The Simpson Desert parks in South Australia and Queensland close each year from 1 December to 15 March, because temperatures can go above 50 degrees Celsius, and the best time to visit is from May to October. Visitors must carry extra fuel, water and food.

The CDC suggests light, loose, light-colored clothing and a wide-brimmed hat in hot places, drinking during exercise, and avoiding hard activity in the hottest part of the day.

NPWS SA: the Simpson parks close from 1 December to 15 March for public safety, as temperatures can exceed 50 °C; autumn, winter and spring are the most enjoyable times (another NPWS page: May to October is ideal); reserves of fuel, water, food, spare parts and recovery gear must be carried, and firewood collection is prohibited because dead wood shelters animals.

CDC Yellow Book: lightweight, loose, light-colored clothing; a wide-brimmed hat markedly reduces radiant heat; drink during exertion but do not force water; avoid strenuous activity in the hottest part of the day.